The true mind can weather all the lies and illusions without being lost. The true heart can though the poison of hatred without being harmed. Since beginning-less time, darkness thrives in the void, but always yields to purifying light.
This is not a decision you will ever be able to live with.
Korra: You really think I can do this?
Tenzin:I have no doubt.
Korra: Thank you for not giving up on me.
Tenzin: I'm proud of you.